USPTO Patents Application 09893292

(12)

UK Patent Application ,„,GB ,,,,2308448 „ 3 ,A

(43) Date of A Publication 25.06.1997

(21) Application No 9607274.9

(22) Date of Filing 09.04.1996

(30) Priority Data
(31) 95052016

(32) 19.12.1995 (33) KR

(71) Applicants)

Samsung Display Devices Co Ltd

(Incorporated in the Republic of Korea)

575 Shin -Dong, PaMaJ-gu, Suwon, Kyunggi-do,
Republic of Korea

(72) Inventorts)

Hyeongdong Kim

(74) Agent and/or Address for Service
W P Thompson ft Co

Celcon House, 289-293 High Hofcorn, LONDON,
WC1V 7HU, United Kingdom

(51) INT a 6

G06K 11/12

(52) UK CL (Edition O )

Q1N NAQB N1D8 N1D9 N3S10 N7S

(56) Documents Cited
GB 2148011 A

GB 2088063 A

US 3911215 A

(58) Field of Search

UK CL (Edition O ) G1N NAGB10 NAQB
INTCL 6 G06K 11/12
Online: WPt

(54) Touch panel

(57) A touch panel with improved resistance to problems of cracking in an upper, resistive layer is made by
substituting a phototransparent organic film 7 for the conventional resistive layer. As described the film 7 is
formed of metal oxide powder in a polymer and has a resistivity of about 300-800 ohms/square. The panel has
a transparent substrate 1 carrying a conductive layer 2, e.g. of indium tin oxide, a spacing layer 3, and the
organic resistive film 7. The latter may be covered by a protective film structure (Fig. 4). The panel is stated to
have an economic advantage in that it can be used perpetually if the conductive film in the lower part is not
impaired.

FIG. 3

>

FIG. 4

TOUCH PANEL 2308448

10

15

20

25

This invention relates to a touch panel, more
particularly, to a touch panel in which the contact
conductive layer is substituted with phototransparent
organic conductive films to give conductivity per se,
thus not requiring coating process of conductive
layer and resolving problems of crack owing to the
conductive layer.

A touch input system including a touch panel
which determines the position of an object which is
in contact with a contact surface, has been used
variously in the fields of computer graphics, design
and manufacturing systems using computers. The touch
system denotes a system consisting of a digitizer
which responds to a touch on a distinctive position
of a contact surface, and can be driven by touching
with a finger of an operator because of a transparent
covering layer on a conductive surface.

The driving principle of a touch panel in the
touch panel system is as follows:

A contact surface of a touch panel has equal
specific electric resistance and is connected to an

1

electrode made of a material of which conductivity is
greater than that of the contact surface. This touch
input system consists of means which applies an
electric potential across a contact surface in the
direction 2 or the direction vertical to the
direction 1 after an electric potential across a
contact surface in the direction 1 is applied*
Consequently, if the contact is touched by a finger
of an operator or an object such as a touch pen, an
electric potential of the touched position is
measured which corresponds to a distance between
positions of the objects on contact surface as well
as a distance between an electrode and an object.
The system consists of means not only providing x-y
coordinates but also determining and providing z axis
value on the basis of parameters of pressure or
position. And dot space plays a role of wrapper for
double film and dot space tip in the dot spaces
damages conductive layer (2') easily by being applied
on the conductive layer (2') heavily to induce crack
of conductive layer, which is caused by the formation
of wrapper and the sharpness of a tip. Therefore by
blunting the formation of wrapper and the sharpness
of the tip using cushion of an adhesive, some
problems of crack are solved, but there still remain
the problems that blunt space tip is difficult to
make and there are no essential countermeasures for
crack on the conductive layer. To solve the

problems, the structure of touch panel double film in
FIGs. 1 and 2 is used. The structure consists of the
conductive layers formed on the upper part of the
base substrate and on the lower part of double film
5 which are separated by insulated dot space (3), and

the lower film coated with the upper film (5') on
both sides thereof, and hardcoating layer thereon.

The touch panel with this structure is operated
according to a principle that coordinate values are
10 recognized using positional change of resistance

values when substrate conductive layer (2) of the
base substrate and contact conductive layer (2') of
film are attached by touching with a touch pen. In
general, glass, plastics or various printer circuit
15 substrate materials, or rigid body such as a metal

with insulated layer are used as the base substrate
(1) and hard plate coated with plastics material in
the form of soft layer thereon, as well.

And conductive layers (2, 2') consist of a
transparent conductive material for which typically
indium tin oxide (ITO) is used. Polyester group
resins such as polyethylene terephtalate (PET) and
polycarbonate are used as the films (5, 5'}.

PIG. l indicates the structure with conductive
layers coated on both sides of the lower film (5) and
PIG. 2 indicates the structure in which only the
substrate conductive layer (2) of the upper part of
the base substrate and the conductive layer attached

20

25

3

thereto are used by coating only one side of the
lower film (5) .

Generally, the film of a thickness of about 25
/an is used as the lower film, and the thickness of
the conductive layer can be adjusted to about 100 A
as a conductive layer having the resistance of 300 n/n
is used.

The crack is solved to some degree using the
double film structure in FIGs. 1 and 2. However, the
problems still remain because the crack of conductive
layer is eventually generated to make an error in
operation by changing the value of resistance, and
particular countermeasures therefor have not been
developed so far.

The object of the present invention is to
resolve problems induced with coating of conductive
layers by providing a touch panel in which the film
coated with a conductive layer is substituted with
the phototransparent organic conductive film.

To achieve the object of the present invention,
provided is a touch panel comprising a substrate (1)
made of a transparent insulated material, a substrate
conductive layer (2) formed on the substrate, a dot
space (3) formed between the substrate conductive
layer and a contact conductive layer (2'), the
contact conductive layer (2') causing change of

10

electric resistance by external contact on the dot
space, wherein the touch panel is characterized in
that the contact conductive layer is consisted of a
phototransparent organic conductive film (7) .

According to the invention, the contact
conductive layer consisted of a phototransparent
conductive film can further comprise a customary
hardcoating layer on the surface thereof to improve
abrasion and friction properties of the

phototransparent conductive film (7), as indicated in
FIG. 3.

In addition, the contact conductive layer
according to the invention can further comprise a
phototransparent conductive .coating layer (2') on one
or both sides of the phototransparent conductive film
(7), as indicated in FIG. 4.

Moreover, the contact conductive layer according
to the invention in FIG. 4 further comprises a
protective film layer (5) such as polyester film
20 thereon.

According to the invention, the phototransparent
organic conductive film can be simply manufactured by
the method that white powder of metal oxides
consisting of indium oxide, antimony oxide, tin
oxide, etc. are added to an ordinary polymer for the
formation of films to have 300 - 800 n/Q of
resistance value of the mixed polymer.

15

25

5

The invention will now be described by way of examp
with reference to the accompanying drawings, in which:
FIG. 1 and FIG* 2 are cross-sectional views of

the conventional double film touch panels.

FIG, 3 is a cross-sectional view of the touch

panel according to example 1 of the present

invention.

FIG. 4 is a cross-sectional view of the touch
panel according to example 2 of the present
invention.

The following is presented as an example but
does not limit the scope of the invention.
Example l

ITO was coated on a transparent insulated
substrate by chemical vapour deposition method
indicated in FIG. 3 to form a transparent conductive
layer, dot spacer of insulated material was formed
thereon, and a thin phototransparent organic
conductive film was hardcoated thereon to manufacture
a touch panel.

Example a

A touch panel was manufactured as the same
process of example 1 except that one more layer of
film is attached onto the thin phototransparent
organic conductive film by an adhesive indicated in
FIG. 4.

Example 3

A touch panel was manufactured as the same
process of example 2 except that ITO was coated on

6

both sides of the thin phototransparent organic
conductive film.

To evaluate the quality of the touch panels
manufactured in the above examples 1 to 3, the
5 resistance property of transparent conductive layer

of the touch panels was measured. The result was
indicated in the following table:

Table

10

resistance property
improvement percentage

15

Example 1

100

Example 2

100

Example 3

95

20

As shown in the above table, the resistance
property of the touch panel according to the present
invention was improved almost completely in
comparison with the touch panels with the double film
structure indicated in FlGs. 1 and 2 of the
conventional method and the problems of the
resistance change for crack were solved. In general,

7

because resistance of phototransparent organic
conductive film of 300 n/Q, which is the resistance
required for a touch panel, was difficult to obtain
(over 80 %) taking into consideration of
phototransmittance , the transparent conductive layers
are coated thereon. More efficient structure of the
touch panel is when phototransmittance and resistance
value of phototransparent organic conductive film is
about 300 - 800 tl/Q* Moreover, the touch panel has
economic advantage because it is capable of being
used permanently if a phototransparent organic
conductive film is not damaged*

8

CLAIMS

1. A touch panel comprising:
a substrate made of a transparent insulated material;
a substrate conductive layer formed on said
5 substrate;

a dot space formed between said substrate conductive
layer and a contact conductive layer; and
a contact conductive layer causing change of electric
resistance by external contact on said dot space.
10 2. The touch panel of claim l, wherein said

contact conductive layer consists of a
phototransparent organic conductive film.

3. The touch panel of claim 2, wherein said
contact conductive layer further comprises a
phototransparent conductive coating layer on one or
both sides of the phototransparent organic conductive
film.

4. The touch panel of claim 2, wherein said
contact conductive layer further comprises a
protective film layer on said phototransparent
organic conductive film.

5. The touch panel of any one of claim 1 to
claim 4, wherein said contact conductive layer
further comprises a hardcoating layer on the surface

25 thereof.

6. The touch panel of claim 2, wherein said
phototransparent organic conductive film is simply
manufactured by the method that white powder of metal

15

20

9

oxides consisting of indium oxide, antimony oxide, or
tin oxide, etc. are added to an ordinary polymer for
the formation of films to have the resistance value
of 300 - 800 n/O of the mixed polymer.

7, a touch panel substantially as described herein,

with reference to the accompanying drawings.

10

Amendments to the claims have been filed as follows

1. A touch panel comprising:

a substrate made of a transparent insulated material;
5 a substrate conductive layer formed on said substrate;

a dot space formed between said substrate conductive
layer; and

a contact conductive layer formed on said dot space
and causing change of electric resistance by external
10 contact on said dot space, wherein said contact conductive
layer consists of a phototransparent organic conductive
film.

2. The touch panel of claim 1, wherein said contact
15 conductive layer further comprises a phototransparent

conductive coating layer on one or both sides of the
phototransparent organic conductive film,

3. The touch panel of claim 1, wherein said contact
20 conductive layer further comprises a protective film layer

on said phototransparent organic conductive film.

4. The touch panel of amy one of claims l to 3, wherein
said contact conductive layer further comprises a

25 hardcoating layer on the surface thereof*

5. The touch panel of claim l f wherein said
phototransparent organic conductive film is simply
manufactured by the method that white powder of metal

30 oxides consisting of indium oxide, antimony oxide, /£>r tin
oxide, etc are added to an ordinary polymer for. the

II

formation of films to have the resistance value of
800 Q/D of the mixed polymer,

6. A touch panel substantially as described herein
reference to the accompanying drawings.

Patent
Office

Application No:
Claims searched:

GB 9607274.9
1-6 as amended

Examiner: M. G. Clarke

Date of search: 28 November 1996

Patents Act 1977

Search Report under Section 17

Databases searched:

UK Patent Office collections, including GB, EP, WO & US patent specifications, in:
UK CI (Ed.O): GIN NAGB10, NAQB
IntCl (Ed.6): G06K 11/12
Other: Online: WPI

Documents considered to be relevant:

Category

Identity of document and relevant passage

Relevant
to claims

A

GB2 148011 A

Toppan Moore Co - see especially
pages 3,4

A

GB2088063A

Robert Branton et al. - see especially pagel
lines 67-126

A

US3911215

assigned to Elographics Inc - whole
document

Document indicating lack of novelty or inventive step A
Documem indi c at ing lick of inventive step if combined P
with one or more other documents of tame category.

E

Member of the same patent family

Document indicating technological background and/or state of the art.
Document published on or after the declared priority date but before
the filing date of this invention.

Patent document published on or after, but with priority date earlier
than, the filing date of this application.

I 3.

An Ex e c ut ive Agency of die Department of Trade and Industry